EP0374428B1 - Compacting screen for a road finisher - Google Patents

Description

The invention relates to a (in practice sometimes referred to as "screed") screed for a (pavement) paver for paving and compacting fresh road building material (such as asphalt) according to the preamble of claim 1 preferably a compaction screed with a main screed, the working width of which can be changed by means of adjustable screeds that can be extended laterally.

Compaction screeds for such (road surface) pavers are known which have a base plate lying flat on the building material to be compacted during the compaction operation and (at least) a ramming unit with a strip-shaped ramming element which extends transversely to the direction of travel, the periodically oscillating driven ramming element ( which is sometimes referred to as "knife") compresses the building material to be compacted due to an impressed movement and the base plate (due to the weight force exerted on it) also contributes to the compacting, in particular, meanwhile, a (surface) smoothing of the laid building material.

Since it is desirable to achieve as high a compaction of the laid building material as possible in order to prevent it from lowering (in particular partially) later when driving on it, various measures have already been proposed in order to achieve such a high compaction.

It is known, for example from DE 33 00 092 A1, to provide a ramming unit which has two interacting ramming elements (with a common eccentric bearing) which are arranged in front of the screed body in the direction of travel in order to achieve the aforementioned goal. In this known compaction screed there is a higher compaction due to the two ramming elements than in the case of a compaction screed which has only a single ramming element, but it has been shown that the object on which the above-mentioned document is based to create such a compaction screed which a subsequent post-compaction of the paving material is not necessary, which cannot be solved with this previously known compaction screed, so that a subsequent final finishing by means of a roller or the like is regularly indispensable even when such a compaction screed is used.

It has been shown, for example, that with two ramming elements arranged directly next to one another in the working area of the second ramming element (instead of a compression effect), a kind of suction effect can occur, in which in particular the fine and liquid components of the building material are sucked up (instead of compressed), and, moreover, the road building material already compacted by the first tamping element can be shaken loose.

DE 32 09 989 A 1 (or the associated main patent according to DE 31 14 049 C 3) has therefore already proposed a generic compaction screed, the (first) base plate of which - in the direction of travel of the paver - has a ramming unit in a conventional manner a strip-shaped ramming element extending transversely to the direction of travel has been placed directly upstream, which during the compression operation periodically moves its underside up to the (height) level of the underside of the (immediately following first) base plate, with a compaction effecting in addition a second compacting device with a strip-shaped (second) compacting element, which also extends transversely to the direction of travel of the paver, is arranged directly behind it, which protrudes downward with its underside over the underside of the first base plate, during the compacting operation on the compactor ement of the second compaction device, post-compacted building material, is immediately arranged on the second base plate.

This generic compaction screed according to DE 32 09 989 A 1 or DE 31 14 049 C 3, however, is not a ramming unit with respect to the second compaction device, but rather a compaction device (already known from US Pat. No. 3,614,916) with a so-called pressure bar with which (only) swelling pressure impulses are to be introduced into the paving material, which are generated by means of a vibration generator or exciter.

It has been assumed that such a (vibration) pressure strip, which is (directly) arranged after the first base plate, actually results in a predetermined compression during (compression) operation, the "geometric dimension" of which is as large as the level difference between the bottom of the first base plate and the underside of the second base plate. Depending on the respective circumstances of the specific application, this is by no means the case on a regular basis. If, however, the second compression device arranged downstream of the first base plate or its (second) compression element only results in a lower compression than theoretically provided due to the periodic swelling pulses introduced into the installation material, it obviously does not occur that the second compression element downstream second base plate rests on the top of the installation material, so that it cannot be effective (smoothing) at all, and it can even happen that the underside of the second compression element (which extends downward beyond the underside of the base plate) inevitably rests on the pre-compacted installation material, which means that even the first base plate does not lie on its rear section at all on the top of the installation material pre-compressed by the ramming unit arranged in front of it, because the base plates are in the frame n the compaction screed has a structurally provided fixed relative position to each other, and this also applies to the second compaction device (and thus its compaction element), which - as stated - in contrast to a tamping element of a tamper unit, which performs a considerable stroke during the compaction operation, only in Within the scope of its vibration, it is subjected to minimal vibratory movements, which only make up a small fraction of the height increment between the first and second base plate and thus also between the first base plate and the underside of the (second) compression element designed as a pressure bar of the second compression device arranged downstream of the first base plate.

The present invention has for its object to improve a compaction screed of the type described in the preamble of claim 1 with a safe high post-compaction or final compaction, in particular with regard to its drive mechanism.

The above object is achieved according to the invention by the characterizing features of claim 1. Preferred configurations are described in the subclaims.

In this regard, it should be pointed out that the features of claims 2 and 3, according to which the ramming elements are driven in push-pull or the ramming units (or their ramming elements) are coupled to one another in terms of drive, according to US-A-1 644 511 for a machine for production a concrete roadway are known per se.

A preferred embodiment is that the lever arms connected to the ramming elements are of different lengths in order to be able to generate different ramming forces on the ramming elements, a preferred embodiment consisting in that the lever arm acting on the rear ramming element is shorter than that with the front ramming element connected lever arm.

In addition, the (tamper) stroke of the tamping element and / or its tamping frequency can preferably be changed in order to adjust the compaction screed according to the invention to different To be able to adjust conditions (especially layers of paving material of different thicknesses)

If, according to a preferred embodiment, the tamper drive only has a working cylinder (preferably designed as a hydraulic cylinder) like a vibration exciter, undesirable, uncontrollable additions or cancellations of the generated vibrations do not occur in the two-arm lever-drive configuration described above, because the vibrations generated by the Compression operation - due to the lever arms of different lengths - results in a difference in vibration mass resulting in vibration amplitudes which act as a uniform vibration on the base plate (s) (in particular the front first base plate), which means that a separate vibration drive (at least) for the front first base plate can also be omitted.

According to another embodiment, the tamper drive can have a rotatingly driven eccentric, which acts on the lever (or the tamper) via a connecting rod, it also having proven to be expedient for adaptation purposes if the eccentricity of the eccentric can be changed to change the tamper stroke.

According to a further highly preferred embodiment of the present invention, at least a portion of the front first base plate can be lowered (and of course lockable in intermediate positions) in a controlled manner down to the level of the underside of the second base plate in order to reduce the height difference to the rear second base plate, this measure in particular for different layer thicknesses of paving material is appropriate. Such a drop, which can preferably take place in that the front first base plate is pivotally mounted about a pivot axis running transversely to the direction of travel, the stroke of the downstream one second ramming element can be rendered ineffective, for example, by lowering the underside of the front first base plate to the level of the rear second base plate, so that the downstream second ramming element no longer protrudes downward over both levels during its operation.

An adjustment of the inclination of the front first base plate, as already arranged above, has the advantage over vertical lowering that a better transition from the front first tamping element to the level of the working surface (= underside) of the rear second base plate can be achieved. Such a pivoting, metered adjustment of the front first base plate can preferably take place by means of an adjustment device with a worm drive, although other adjustment devices such as a stepping motor, an adjustment screw, spindle or the like can obviously also be provided.

According to a further preferred embodiment of the present invention, the radial distance of the front edge of the front first base plate pointing in the direction of travel of the paver to the pivot axis is smaller than the distance of the rear edge of the first base plate facing the rear second base plate, so that the rear edge can be lowered by a Adjustment of the inclination of the first base plate to make the downstream second tamper ineffective, in whole or in part.

The ramming elements are preferably beveled in a manner known per se on their lower front edges pointing in the direction of travel, the beveling of the front first ramming element being able to have a larger angle to the horizontal than the beveling of the rear second ramming element, for example 45 ° / 30 °.

A retrofitting of conventional pavers with the compaction screed according to the invention and a replacement of a compaction screed for repair purposes is achieved according to a development of the present invention in that the front first base plate and the ramming units form an exchangeable structural unit.

The invention is explained below using exemplary embodiments with reference to a drawing.

Fig. 1

einen Vertikalschnitt durch eine erfindungsgemäße Verdichtungsbohle;

Fig. 2

einen Ausschnitt aus der Darstellung gemäß Fig. 1 in vergrößerter Darstellung;

Fig. 3

einen Vertikalschnitt durch ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Verdichtungsbohle;

Fig. 4

einen Schnitt durch das Ausführungsbeispiel gemäß Fig. 3 in Richtung der Schnittlinie IV-IV gesehen; und

Fig. 5

einen Vertikalschnitt durch ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Verdichtungsbohle.

It shows:

Fig. 1

a vertical section through a compaction screed according to the invention;

Fig. 2

a section of the illustration of Figure 1 in an enlarged view.

Fig. 3

a vertical section through a further embodiment of a compaction screed according to the invention;

Fig. 4

seen a section through the embodiment of FIG 3 in the direction of section line IV-IV. and

Fig. 5

a vertical section through a further embodiment of a screed according to the invention.

Fig. 1 shows a vertical section through a compaction screed 1 'with a compaction bar 1, which has a - in the direction of travel 4 forward - front first base plate 2, which lies flat on the building material (= paving material) during operation and on this acts (see Fig. 2).

The first base plate 2 is immediately preceded by a ramming unit 5 which effects a pre-compaction and has a strip-shaped tamping element 5 'which extends transversely to the direction of travel 4 and which periodically moves with its underside 23 during the compaction operation to the level 24 of the underside 25 of the first base plate 2 is.

The first base plate 2 is immediately followed by a second tamping unit which brings about a compaction and has a strip-shaped (second) ramming element 6 'which also extends transversely to the direction of travel 4. The two ramming elements 5 ', 6' each have bevels 5a or 6a on their front (bottom), the bevel 5a of the first ramming element 5 'lying in the direction of travel 4 not being as steep in relation to the horizontal as the bevel 6a of the first base plate 2 immediately downstream second ramming element 6 '.

The two ramming elements 5 ', 6' are connected to one another via a two-armed (rocker) lever 7, which is pivotally mounted about an axis of rotation 8. The drive for the ramming units 5, 6 or their ramming elements 5 ', 6', not shown in the drawing for the sake of a better overview, engages on a tab 9, so that the two ramming elements 5 ', 6' periodically oscillate to an up and down Downward movement are driven when the lever 7 tilts back and forth about its pivot axis 8.

The lever arm 7a, on which the ramming element 5 'arranged in the direction of travel 4 is arranged, is longer than the lever arm 7b, on which the ramming element 6' is arranged, so that the two ramming units 5, 6 are different Exercise ramming forces.

The compression bar 1 is pivotable about a pivot axis 11 in the direction of arrow 12, i. H. can be lowered with its section facing the ramming unit 6 and thus its inclination adjustable.

The above explanations can be seen in particular from FIG. 2, which shows an enlarged partial representation of the representation according to FIG. 1.

As can be seen from FIG. 1, the compaction screed 1 'has a so-called main screed 13 which, in order to adjust / adjust the working width, has four adjustment beams which can be extended laterally and which also form components of the compaction screed 1', the main screed 13 and the adjustable screeds to be arranged in room 14, which are not shown in the drawing, are basically constructed in the same way.

In Fig. 1 it is indicated by dashed lines 2a that the front first base plate 2 can be adjusted in its inclination about the pivot axis 11. A spindle 17 is provided for adjusting the compression bar 1 - and thus the front first base plate 2.

In Fig. 1 is also indicated by dashed lines how the ramming elements 5 ', 6' move about the pivot axis 8, the ramming units 5, 6 or their ramming elements 5 ', 6' are driven by an eccentric shaft 16, which via a connecting rod 15 is connected to the tab 9 of the lever 7.

Furthermore, it can be seen in FIG. 1 that the tamping element 6 ′ of the second tamper unit 6 has an underside 26 over the underside 25 of the first base plate 2 Downwardly protruding second base plate 18 is immediately arranged during the compression operation on the building material which is re-compressed by the ramming element 6 'of the second ramming unit 6. It can also be seen from FIG. 1 that the second ramming element 6 'in its upward and downward movement reaches down to the working surface of the rear second base plate 18 which is in engagement with the building material 3.

The inclination of the front first base plate 2 is also adjustable such that its rear area can be lowered to the level of the working surface of the rear second base plate 18.

FIG. 3 shows a variant compared to the exemplary embodiment according to FIG. 1, an adjusting screed 14 ′ being provided in addition to the main screed 13. The embodiment of the main screed 13 according to FIG. 3 differs from the embodiment according to FIG. 1 only by another adjustment device for the compression bar 1, which in this embodiment has a working cylinder 19 instead of a spindle 17.

FIG. 4 shows a section through the compaction screed according to FIG. 3 in the direction of the section line IV-IV in FIG. 3, but only one half of the main screed 13. On the left side of FIG. 3 there is the center of the main screed 13; here the main screed 13 actually continues to the left.

The main screed 13 could in principle be of any previously described or similar configuration, a main screed 13 according to FIG. 3 being shown here.

It can be seen that the compression bar 1 over Working cylinder 19 is adjustable without changing the tamper mounting, since the compression bar 1 is suspended separately from the tamper via the working cylinder 19.

It can also be seen how the eccentric shaft 16 and the tab 9 of the lever 7 are constructed. It can be seen in particular that the eccentric shaft 16 is eccentric in the area in which it is encompassed by the connecting rod 15, and that in addition to this predetermined eccentricity there is the eccentricity of a bearing shell 21 which surrounds the eccentric shaft 16 in this area . This bearing shell 21 can be rotated coaxially about the eccentric shaft 16. The set eccentricity is fixed with a disk 22.

Depending on the rotational position of the eccentric shaft 16 and the bearing shell 21 relative to one another, the eccentricities of the eccentric shaft 16 and the bearing shell 21 add or subtract, so that the eccentric formed by the eccentric shaft 16 and the bearing shell 21, which is encompassed by the eye of the connecting rod 15, its eccentricity can be changed, a change in this eccentricity causing a change in the tamper stroke of the ramming units 5, 6 or their ramming elements 5 ', 6'.

Furthermore, a clutch 23 'is indicated in FIG. 4, through which the eccentric shaft 16 is driven in an actively rotating manner.

5 finally shows a further (third) exemplary embodiment of a compaction screed 1 'according to the invention, which is distinguished from the exemplary embodiments described above by a modified embodiment of its adjusting device, the adjusting device in FIG. 5 being an oil motor 20 with a worm gear shows.

REFERENCE SIGN LIST

1

Compression bars

1'

Compaction screed

2nd

(front) first base plate

3rd

Building material (= paving material)

4th

Arrow (direction of travel of the paver)

5

(Front) first tamper unit

5 '

Ramming element (of 5)

5a

Bevel (of 5)

6

(rear) second tamper unit

6 '

Ramming element (of 6)

6a

Bevel (from 6 ')

7

(two-armed toggle) lever

7a

Lever arm (at 5 ')

7b

Lever arm (at 6 ')

8th

Swivel axis (of 7)

9

Tab

10th

11

Swivel axis

12th

Arrow (swivel direction)

13

Main screed

14

room

14 '

Adjustable screed (Fig. 3)

15

Connecting rod

16

Eccentric shaft

17th

spindle

18th

second base plate

19th

Working cylinder

20th

Oil engine (Fig. 5)

21

Bearing shell

22

disc

23

Bottom (from 5 ')

23 '

clutch

24th

Level (out of 25)

25th

Bottom (of 2)

26

Bottom (from 18)

27

Bottom (from 6 ')

28

Height level of 26

Claims (17)

1. A compacting screen for a road finisher,

   a) comprising a first baseplate (2) acting flatly on the road material,

   b) which baseplate (2) (in the direction of travel (4) of the finisher)

   b1) is immediately preceded by a first compacting means (tamping unit) (5) comprising a first tamping element (5') in the form of a strip extending transversely of the direction of travel (4), the underside of the first tamping element (5') being periodically moved as far as the level (24) of the underside (25) of the first baseplate (2), and

   b2) is immediately followed by a second compacting means (tamping unit) (6) comprising a second tamping element (6') in the form of a strip extending transversely of the direction of travel (4), the underside (27) of said tamping element (6') being periodically moved as far as the level (28) of the underside (26) of the second baseplate (18), and

   b3) which is immediately followed by a second baseplate (18) the underside (26) of which projects down beyond the underside (25) of the first baseplate (2), the underside (25) of the first baseplate (2) being disposed higher than the underside (26) of the second baseplate (18) by an amount corresponding to the maximum (tamping) travel of the second tamping element (6'),

   characterised in that
   the tamping elements (5', 6') are interconnected via a two-arm (rocking) lever (7), each tamping element (5', 6') being connected to one of the two lever arms (7a, 7b) respectively and the lever (7) being drivable in oscillation about its mounting axis (8).
2. A compacting screen according to claim 1, characterised in that the tamping elements (5', 6') are driven in opposition to one another.
3. A compacting screen according to claim 1 or 2, characterised in that the tamping units (5, 6) or their tamping elements (5', 6') are coupled together in terms of drive.
4. A compacting screen according to any one of claims 1 to 3, characterised in that the lever arms (7a, 7b) connected to the tamping elements (5', 6') are of different lengths.
5. A compacting screen according to claim 4, characterised in that the lever arm (7b) engaging the rear second tamping element (7') is shorter than the lever arm (7a) connected to the front first tamping element (5').
6. A compacting screen according to one or more of the preceding claims, characterised in that the (tamper) travel of the tamping elements (5', 6') is variable.
7. A compacting screen according to one or more of the preceding claims, characterised in that the tamping frequency of the tamping elements (5', 6') is variable.
8. A compacting screen according to one or more of the preceding claims, characterised in that the tamper drive comprises a working cylinder (preferably a hydraulic cylinder) and a means for oscillatory excitation of its piston.
9. A compacting screen according to one or more of claims 1 to 7, characterised in that the tamper drive comprises an eccentric (16, 21) which is driven in rotation and which acts on the lever (7) or the tamping elements (5', 6') via a connecting rod (15).
10. A compacting screen according to claims 6 and 9, characterised in that the eccentricity of the eccentric (16, 21) is variable.
11. A compacting screen according to one or more of the preceding claims, characterised in that at least a portion of the first baseplate (2) is controllably lowerable as far as the level (28) of the underside (26) of the second baseplate (18).
12. A compacting screen according to claim 11, characterised in that the front first baseplate (2) is mounted to rock about an axis (11) extending transversely of the direction of travel (4).
13. A compacting screen according to claim 11 or 12, characterised in that for its controlled lowering the front baseplate (2) is connected to an adjustment means comprising a worm drive.
14. A compacting screen according to claim 12 or 13, characterised in that the radial distance of the front edge of the front first baseplate (2) from the rocking axis (11) is less than the distance of its rear edge.
15. A compacting screen according to one or more of the preceding claims, characterised in that the tamping elements (5', 6') have bevelled front edges in manner known per se.
16. A compacting screen according to claim 15, characterised in that the bevel (5a) of the front first tamping element (5') has a larger angle to the horizontal than the bevel (6a) of the rear second tamping element (6').
17. A compacting screen according to one or more of the preceding claims, characterised in that the front baseplate (2) and the tamping units (5, 6) form an interchangeable unit.

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